Recently, a method for transmitting high-efficiency compression coded data based on a modified discrete cosine transform (MDCT) has been widely used as a method for efficiently transmitting audio data. In this method, an audio signal is divided into frames, the MDCT is performed on the frames, the number of quantization bits are assigned to an MDCT coefficient based on a psychological audio model, the MDCT coefficient is quantized and transmitted. Thus, audio data can be transmitted using a small number of transmission bands by efficiently compressing and coding data.
A typical example is the MPEG (Moving Picture Expert Group)-4 AAC (Advanced Audio Coding), etc.